Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D493/00—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system
  • C07D493/02—Heterocyclic compounds containing oxygen atoms as the only ring hetero atoms in the condensed system in which the condensed system contains two hetero rings
  • C07D493/08—Bridged systems
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C221/00—Preparation of compounds containing amino groups and doubly-bound oxygen atoms bound to the same carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C223/00—Compounds containing amino and —CHO groups bound to the same carbon skeleton
  • C07C223/02—Compounds containing amino and —CHO groups bound to the same carbon skeleton having amino groups bound to acyclic carbon atoms of the carbon skeleton
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D221/00—Heterocyclic compounds containing six-membered rings having one nitrogen atom as the only ring hetero atom, not provided for by groups C07D211/00 - C07D219/00
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
  • C07D487/04—Ortho-condensed systems
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D519/00—Heterocyclic compounds containing more than one system of two or more relevant hetero rings condensed among themselves or condensed with a common carbocyclic ring system not provided for in groups C07D453/00 or C07D455/00

Definitions

• the invention pertains to the field of chemical synthesis. More particularly, the invention pertains to methods for the synthesis of substituted salicylaldehyde derivatives using an anhydro dimer intermediate.
• Salicylaldehyde 1 and its derivatives are widely used chemicals finding applications in many fields including the synthesis of pharmaceuticals and other biologically active molecules and in the formation of ligands for organometallic compounds used in catalysis and other processes.
• a common approach to this problem is to synthesize a substituted phenol bearing the functionality required in the final salicylaldehyde derivative and then perform a formylation reaction to introduce the aldehyde group ortho to the phenolic oxygen to form the required salicylaldehyde.
• a formylation reaction to introduce the aldehyde group ortho to the phenolic oxygen to form the required salicylaldehyde.
• formylation reactions often suffer from moderate yields and/or the formation of undesired side-products.
• the present invention provides a solution to this and other related problems.
• the present invention encompasses the recognition that anhydro dimers of salicylaldehyde and its derivatives can act as convenient synthetic intermediates that mask the reactivity of the ortho-formyl phenol moiety.
• the invention includes methods of intentionally forming these dimers, performing chemistry on the aryl rings or substituents of the dimerized salicylaldehyde derivatives and then hydrolyzing the dimers to liberate two molecules of the transformed salicylaldehyde derivate.
• the present invention provides, among other things, methods of synthesizing salicylaldehyde derivatives comprising the steps of: a) providing salicylaldehyde or a derivative thereof, b) forming an anhydro dimer of the provided salicylaldehyde compound, c) performing one or more chemical transformations on the anhydro dimer and d) hydrolyzing the anhydro dimer to provide a salicylaldehyde derivative different from that provided in step (a).
• the present invention also encompasses methods of making such salicylaldehyde anhydro dimers.
• compositions of matter comprising novel salicylaldehyde dimers.
• such salicylaldehyde dimers have particular utility in the synthesis of catalysts and, in particular, of salen-type catalysts.
• such salicylaldehyde dimers have particular utility in the synthesis of biologically active molecules.
• Certain compounds of the present invention can comprise one or more asymmetric centers, and thus can exist in various stereoisomeric forms, e.g., enantiomers and/or diastereomers.
• inventive compounds and compositions thereof may be in the form of an individual enantiomer, diastereomer or geometric isomer, or may be in the form of a mixture of stereoisomers.
• the compounds of the invention are enantiopure compounds.
• mixtures of enantiomers or diastereomers are provided.
• certain compounds, as described herein may have one or more double bonds that can exist as either the Z or E isomer, unless otherwise indicated.
• the invention additionally encompasses the compounds as individual isomers substantially free of other isomers and alternatively, as mixtures of various isomers, e.g., racemic mixtures of enantiomers.
• isomers includes any and all geometric isomers and stereoisomers.
• “isomers” include cis- and trans-isomers, E- and Z-isomers, R- and S-enantiomers, diastereomers, ( D )-isomers, ( L )-isomers, racemic mixtures thereof, and other mixtures thereof, as falling within the scope of the invention.
• a stereoisomer may, in some embodiments, be provided substantially free of one or more corresponding stereoisomers, and may also be referred to as “stereochemically enriched.”
• a particular enantiomer may, in some embodiments be provided substantially free of the opposite enantiomer, and may also be referred to as “optically enriched.”
• “Optically enriched,” as used herein, means that the compound is made up of a significantly greater proportion of one enantiomer. In certain embodiments the compound is made up of at least about 90% by weight of a preferred enantiomer. In other embodiments the compound is made up of at least about 95%, 98%, or 99% by weight of a preferred enantiomer.
• Preferred enantiomers may be isolated from racemic mixtures by any method known to those skilled in the art, including chiral high pressure liquid chromatography (HPLC) and the formation and crystallization of chiral salts or prepared by asymmetric syntheses.
• HPLC high pressure liquid chromatography
• Jacques, et al. Enantiomers, Racemates and Resolutions (Wiley Interscience, New York, 1981); Wilen, S. H., et al., Tetrahedron 33:2725 (1977); Eliel, E. L. Stereochemistry of Carbon Compounds (McGraw-Hill, N.Y., 1962); Wilen, S. H. Tables of Resolving Agents and Optical Resolutions p. 268 (E. L. Eliel, Ed., Univ. of Notre Dame Press, Notre Dame, Ind. 1972).
• halo and “halogen” as used herein refer to an atom selected from fluorine (fluoro, —F), chlorine (chloro, —Cl), bromine, (bromo, —Br), and iodine (iodo, —I).
• aliphatic or “aliphatic group”, as used herein, denotes a hydrocarbon moiety that may be straight-chain (i.e., unbranched), branched, or cyclic (including fused, bridging, and spiro-fused polycyclic) and may be completely saturated or may contain one or more units of unsaturation, but which is not aromatic. Unless otherwise specified, aliphatic groups contain 1-30 carbon atoms. In certain embodiments, aliphatic groups contain 1-12 carbon atoms. In certain embodiments, aliphatic groups contain 1-8 carbon atoms. In certain embodiments, aliphatic groups contain 1-6 carbon atoms. In some embodiments, aliphatic groups contain 1-5 carbon atoms.
• aliphatic groups contain 1-4 carbon atoms. In some embodiments, aliphatic groups contain 1-3 carbon atoms. In some embodiments, aliphatic groups contain 1-2 carbon atoms. Suitable aliphatic groups include, but are not limited to, linear or branched, alkyl, alkenyl, and alkynyl groups, and hybrids thereof such as (cycloalkyl)alkyl, (cycloalkenyl)alkyl or (cycloalkyl)alkenyl.
• cycloaliphatic refers to a saturated or partially unsaturated cyclic aliphatic monocyclic or bicyclic ring systems, as described herein, having from 3 to 12 members, wherein the aliphatic ring system is optionally substituted as defined above and described herein.
• Cycloaliphatic groups include, without limitation, cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl, cycloheptenyl, cyclooctyl, cyclooctenyl, and cyclooctadienyl.
• the cycloalkyl has 3-6 carbons.
• cycloaliphatic also include aliphatic rings that are fused to one or more aromatic or nonaromatic rings, such as decahydronaphthyl or tetrahydronaphthyl, where the radical or point of attachment is on the aliphatic ring.
• aromatic or nonaromatic rings such as decahydronaphthyl or tetrahydronaphthyl, where the radical or point of attachment is on the aliphatic ring.
• 3- to 8-membered carbocycle refers to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring.
• the terms “3- to 14-membered carbocycle” and “C 3-14 carbocycle” refer to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring, or a 7- to 14-membered saturated or partially unsaturated polycyclic carbocyclic ring.
• the term “C 3-20 carbocycle” refers to a 3- to 8-membered saturated or partially unsaturated monocyclic carbocyclic ring, or a 7- to 20-membered saturated or partially unsaturated polycyclic carbocyclic ring.
• alkyl refers to saturated, straight- or branched-chain hydrocarbon radicals derived from an aliphatic moiety containing between one and six carbon atoms by removal of a single hydrogen atom. Unless otherwise specified, alkyl groups contain 1-12 carbon atoms. In certain embodiments, alkyl groups contain 1-8 carbon atoms. In certain embodiments, alkyl groups contain 1-6 carbon atoms. In some embodiments, alkyl groups contain 1-5 carbon atoms. In some embodiments, alkyl groups contain 1-4 carbon atoms. In certain embodiments, alkyl groups contain 1-3 carbon atoms. In some embodiments, alkyl groups contain 1-2 carbon atoms.
• alkyl radicals include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, sec-butyl, sec-pentyl, iso-pentyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, n-decyl, n-undecyl, dodecyl, and the like.
• alkenyl denotes a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon double bond by the removal of a single hydrogen atom. Unless otherwise specified, alkenyl groups contain 2-12 carbon atoms. In certain embodiments, alkenyl groups contain 2-8 carbon atoms. In certain embodiments, alkenyl groups contain 2-6 carbon atoms. In some embodiments, alkenyl groups contain 2-5 carbon atoms. In some embodiments, alkenyl groups contain 2-4 carbon atoms. In some embodiments, alkenyl groups contain 2-3 carbon atoms. In some embodiments, alkenyl groups contain 2 carbon atoms. Alkenyl groups include, for example, ethenyl, propenyl, butenyl, 1-methyl-2-buten-1-yl, and the like.
• alkynyl refers to a monovalent group derived from a straight- or branched-chain aliphatic moiety having at least one carbon-carbon triple bond by the removal of a single hydrogen atom. Unless otherwise specified, alkynyl groups contain 2-12 carbon atoms. In certain embodiments, alkynyl groups contain 2-8 carbon atoms. In certain embodiments, alkynyl groups contain 2-6 carbon atoms. In some embodiments, alkynyl groups contain 2-5 carbon atoms. In some embodiments, alkynyl groups contain 2-4 carbon atoms. In some embodiments, alkynyl groups contain 2-3 carbon atoms. In some embodiments, alkynyl groups contain 2 carbon atoms. Representative alkynyl groups include, but are not limited to, ethynyl, 2-propynyl (propargyl), 1-propynyl, and the like.
• aryl used alone or as part of a larger moiety as in “aralkyl”, “aralkoxy”, or “aryloxyalkyl”, refers to monocyclic and polycyclic ring systems having a total of five to 20 ring members, wherein at least one ring in the system is aromatic and wherein each ring in the system contains three to twelve ring members.
• aryl may be used interchangeably with the term “aryl ring”.
• aryl refers to an aromatic ring system which includes, but is not limited to, phenyl, biphenyl, naphthyl, anthracyl and the like, which may bear one or more substituents.
• aryl is a group in which an aromatic ring is fused to one or more additional rings, such as benzofuranyl, indanyl, phthalimidyl, naphthimidyl, phenantriidinyl, or tetrahydronaphthyl, and the like.
• the term “8- to 14-membered aryl” refers to an 8- to 14-membered polycyclic aryl ring.
• heteroatom refers to nitrogen, oxygen, or sulfur, and includes any oxidized form of nitrogen or sulfur, and any quaternized form of a basic nitrogen.
• Heteroaryl groups include, without limitation, thienyl, furanyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, oxadiazolyl, thiazolyl, isothiazolyl, thiadiazolyl, pyridyl, pyridazinyl, pyrimidinyl, pyrazinyl, indolizinyl, purinyl, naphthyridinyl, benzofuranyl and pteridinyl.
• heteroaryl and “heteroar-”, as used herein, also include groups in which a heteroaromatic ring is fused to one or more aryl, cycloaliphatic, or heterocyclyl rings, where the radical or point of attachment is on the heteroaromatic ring.
• Nonlimiting examples include indolyl, isoindolyl, benzothienyl, benzofuranyl, dibenzofuranyl, indazolyl, benzimidazolyl, benzthiazolyl, quinolyl, isoquinolyl, cinnolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, 4H-quinolizinyl, carbazolyl, acridinyl, phenazinyl, phenothiazinyl, phenoxazinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, and pyrido[2,3-b]-1,4-oxazin-3(4H)-one.
• heteroaryl group may be mono- or bicyclic.
• heteroaryl may be used interchangeably with the terms “heteroaryl ring”, “heteroaryl group”, or “heteroaromatic”, any of which terms include rings that are optionally substituted.
• heteroarylkyl refers to an alkyl group substituted by a heteroaryl, wherein the alkyl and heteroaryl portions independently are optionally substituted.
• the term “5- to 10-membered heteroaryl” refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 10-membered bicyclic heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• the term “5- to 12-membered heteroaryl” refers to a 5- to 6-membered heteroaryl ring having 1 to 3 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or an 8- to 12-membered bicyclic heteroaryl ring having 1 to 4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• heterocycle As used herein, the terms “heterocycle”, “heterocyclyl”, “heterocyclic radical”, and “heterocyclic ring” are used interchangeably and refer to a stable 5- to 7-membered monocyclic or 7- to 14-membered bicyclic heterocyclic moiety that is either saturated or partially unsaturated, and having, in addition to carbon atoms, one or more, preferably one to four, heteroatoms, as defined above.
• nitrogen includes a substituted nitrogen.
• the nitrogen in a saturated or partially unsaturated ring having 0-3 heteroatoms selected from oxygen, sulfur or nitrogen, the nitrogen may be N (as in 3,4-dihydro-2H-pyrrolyl), NH (as in pyrrolidinyl), or + NR (as in N-substituted pyrrolidinyl).
• the term “3- to 7-membered heterocyclic” refers to a 3- to 7-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• the term “3- to 8-membered heterocycle” refers to a 3- to 8-membered saturated or partially unsaturated monocyclic heterocyclic ring having 1 to 2 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• a heterocyclic ring can be attached to its pendant group at any heteroatom or carbon atom that results in a stable structure and any of the ring atoms can be optionally substituted.
• saturated or partially unsaturated heterocyclic radicals include, without limitation, tetrahydrofuranyl, tetrahydrothienyl, pyrrolidinyl, pyrrolidonyl, piperidinyl, pyrrolinyl, tetrahydroquinolinyl, tetrahydroisoquinolinyl, decahydroquinolinyl, oxazolidinyl, piperazinyl, dioxanyl, dioxolanyl, diazepinyl, oxazepinyl, thiazepinyl, morpholinyl, and quinuclidinyl.
• heterocycle refers to an alkyl group substituted by a heterocyclyl, wherein the alkyl and heterocyclyl portions independently are optionally substituted.
• partially unsaturated refers to a ring moiety that includes at least one double or triple bond.
• partially unsaturated is intended to encompass rings having multiple sites of unsaturation, but is not intended to include aryl or heteroaryl moieties, as herein defined.
• protecting group it is meant that a particular functional moiety, e.g., O, S, or N, is masked or blocked, permitting, if desired, a reaction to be carried out selectively at another reactive site in a multifunctional compound.
• a protecting group reacts selectively in good yield to give a protected substrate that is stable to the projected reactions; the protecting group is preferably selectively removable by readily available, preferably non-toxic reagents that do not attack the other functional groups; the protecting group forms a separable derivative (more preferably without the generation of new stereogenic centers); and the protecting group will preferably have a minimum of additional functionality to avoid further sites of reaction.
• hydroxyl protecting groups include methyl, methoxylmethyl (MOM), methylthiomethyl (MTM), t-butylthiomethyl, (phenyldimethylsilyl)methoxymethyl (SMOM), benzyloxymethyl (BOM), p-methoxybenzyloxymethyl (PMBM), (4-methoxyphenoxy)methyl (p-AOM), guaiacolmethyl (GUM), t-butoxymethyl, 4-pentenyloxymethyl (POM), siloxymethyl, 2-methoxyethoxymethyl (MEM), 2,2,2-trichloroethoxymethyl, bis(2-chloroethoxy)methyl, 2-(trimethylsilyl)ethoxymethyl (SEMOR), tetrahydropyranyl (THP), 3-bromotetrahydropyranyl, tetrahydrothiopyranyl, 1-methoxycyclohexyl, 4-methoxytetrahydropyranyl (MTHP), 4-
• protecting groups are detailed herein, however, it will be appreciated that the present disclosure is not intended to be limited to these protecting groups; rather, a variety of additional equivalent protecting groups can be readily identified using the above criteria and utilized in the method of the present disclosure. Additionally, a variety of protecting groups are described by Greene and Wuts (infra).
• compounds of the invention may contain “optionally substituted” moieties.
• substituted whether preceded by the term “optionally” or not, means that one or more hydrogens of the designated moiety are replaced with a suitable substituent.
• an “optionally substituted” group may have a suitable substituent at each substitutable position of the group, and when more than one position in any given structure may be substituted with more than one substituent selected from a specified group, the substituent may be either the same or different at every position.
• Combinations of substituents envisioned by this invention are preferably those that result in the formation of stable or chemically feasible compounds.
• stable refers to compounds that are not substantially altered when subjected to conditions to allow for their production, detection, and, in certain embodiments, their recovery, purification, and use for one or more of the purposes disclosed herein.
• Suitable monovalent substituents on a substitutable carbon atom of an “optionally substituted” group are independently halogen; —(CH 2 ) 0-4 R ⁇ ; —(CH 2 ) 0-4 OR ⁇ ; —O—(CH 2 ) 0-4 C(O)OR ⁇ ; —(CH 2 ) 0-4 CH(OR ⁇ ) 2 ; —(CH 2 ) 0-4 SR ⁇ ; —(CH 2 ) 0-4 Ph, which may be substituted with R ⁇ ; —(CH 2 ) 0-4 O(CH 2 ) 0-1 Ph which may be substituted with R ⁇ ; —CH ⁇ CHPh, which may be substituted with R ⁇ ; —NO 2 ; —CN; —N 3 ; —(CH 2 ) 0-4 N(R ⁇ ) 2 ; —(CH 2 ) 0-4 N(R ⁇ )C(O)R ⁇ ; —
• Suitable monovalent substituents on R ⁇ are independently halogen, —(CH 2 ) 0-2 R ⁇ , -(haloR ⁇ ), —(CH 2 ) 0-2 OH, —(CH 2 ) 0-2 OR ⁇ , —(CH 2 ) 0-2 CH(OR ⁇ ) 2 ; —O(haloR ⁇ ), —CN, —N 3 , —(CH 2 ) 0-2 C(O)R ⁇ , —(CH 2 ) 0-2 C(O)OH, —(CH 2 ) 0-2 C(O)OR ⁇ , —(CH 2 ) 0-4 C(O)N(R ⁇ ) 2 ; —(CH 2 ) 0-2 SR ⁇ , —(CH 2 ) 0-2 SH, —(CH 2 ) 0-2 NH
• Suitable divalent substituents on a saturated carbon atom of an “optionally substituted” group include the following: ⁇ O, ⁇ S, ⁇ NNR* 2 , ⁇ NNHC(O)R*, —NNHC(O)OR*, —NNHS(O) 2 R*, ⁇ NR*, —NOR*, —O(C(R* 2 )) 2-3 O—, or —S(C(R* 2 )) 2-3 S—, wherein each independent occurrence of R* is selected from hydrogen, C 1-6 aliphatic which may be substituted as defined below, or an unsubstituted 5-6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• Suitable divalent substituents that are bound to vicinal substitutable carbons of an “optionally substituted” group include: —O(CR* 2 ) 2-3 O—, wherein each independent occurrence of R* is selected from hydrogen, C 1-6 aliphatic which may be substituted as defined below, or an unsubstituted 5- to 6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• Suitable substituents on the aliphatic group of R* include halogen, —R ⁇ , -(haloR ⁇ ), —OH, —OR ⁇ , —O(haloR ⁇ ), —CN, —C(O)OH, —C(O)OR ⁇ , —NH 2 , —NHR ⁇ , —NR ⁇ 2 , or —NO 2 , wherein each R ⁇ is unsubstituted or where preceded by “halo” is substituted only with one or more halogens, and is independently C 1-4 aliphatic, —CH 2 Ph, —O(CH 2 ) 0-1 Ph, or a 5- to 6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• Suitable substituents on a substitutable nitrogen of an “optionally substituted” group include —R ⁇ , —NR ⁇ 2 , —C(O)R ⁇ , —C(O)OR ⁇ , —C(O)C(O)R ⁇ , C(O)CH 2 C(O)R ⁇ , —S(O) 2 R ⁇ , —S(O) 2 NR ⁇ 2 , —C(S)NR ⁇ 2 , —C(NH)NR ⁇ 2 , or —N(R ⁇ )S(O) 2 R ⁇ ; wherein each R ⁇ is independently hydrogen, C 1-6 aliphatic which may be substituted as defined below, unsubstituted —OPh, or an unsubstituted 5- to 6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur, or, notwithstanding the definition above, two independent occurrences of
• Suitable substituents on the aliphatic group of R ⁇ are independently halogen, —R ⁇ , -(haloR ⁇ ), —OH, —OR ⁇ , —O(haloR ⁇ ), —CN, —C(O)OH, —C(O)OR ⁇ , —NH 2 , —NHR ⁇ , —NR ⁇ 2 , or —NO 2 , wherein each R ⁇ is unsubstituted or where preceded by “halo” is substituted only with one or more halogens, and is independently C 1-4 aliphatic, —CH 2 Ph, —O(CH 2 ) 0-1 Ph, or a 5- to 6-membered saturated, partially unsaturated, or aryl ring having 0-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur.
• substituents are shown attached to a bond which crosses another bond of a depicted molecule. This means that one or more of the substituents may be attached to the molecule at any available position (usually in place of a hydrogen atom of the parent structure). In cases where an atom of a molecule so substituted has two substitutable positions, two groups may be present on the same atom. When more than one substituent is present, each is defined independently of the others, and each may have a different structure. In cases where the substituent shown crossing a bond of the molecule is —R, this has the same meaning as if the ring were said to be “optionally substituted” as described in the preceding paragraph.
• salicylaldehyde as used herein means any substituted or unsubstituted 2-hydroxybenzaldehyde.
• anhydro dimer refers to a molecule formed from the reaction of two molecules of an ortho formyl phenol via the loss of water. While this dimer is shown in the specification to have a specific defined structure, the methods disclosed herein are not limited to this precise structure and therefore encompass other dimeric or pseudodimeric compounds that might be formed.
• chemical transformation refers to any chemical reaction that may be performed on an anhydro dimer. In some embodiments, such chemical transformations do not cause a substantial degree of undesirable reaction on the bicyclic acetal moiety of the anhydro dimer and that any functional groups introduced are substantially compatible with the chemistry employed in hydrolysis of the dimers to recover the salicylaldehyde products.
• chemical transformations performed on anhydro dimers include carbon-carbon bond forming reactions such as alkylations, arylations and acylations; carbon-heteroatom bond forming reactions including, but not limited to halogenation, nitration, oxidation, silylation, metallation, and the like, as well as transformations of functional groups present on the aryl rings including, but not limited to: oxidations, reductions, additions, protections, deprotections, cycloadditions, aminations, decarboxylations, Click reactions, transition metal-catalyzed couplings, metatheses, alkylations, esterifications, hydrogenations, coupling reactions and the like.
• TBD as used herein refers to 1,5,7-Triazabicyclo[4.4.0]dec-5-ene.
• the present invention encompasses methods of synthesizing salicylaldehyde derivatives comprising the steps of: a) providing salicylaldehyde or a derivative thereof, b) forming an anhydro dimer of the provided salicylaldehyde compound, c) performing one or more chemical transformations on the anhydro dimer and d) hydrolyzing the anhydro dimer to provide a salicylaldehyde derivative different from that provided in step (a).
• a provided method comprises the steps of a) providing salicylaldehyde or a derivative thereof, and b) forming an anhydro dimer of a provided salicylaldehyde compound. In certain embodiments, a provided method further comprises the step of performing one or more chemical transformations on an anhydro dimer. In some embodiments, a provided method further comprises the step of hydrolyzing an anhydro dimer to provide a salicylaldehyde derivative different from that provided in step (a).
• a provided method comprises the steps of a) dehydrating a salicylaldehyde to form an anhydro dimer, b) alkylating at least one aromatic ring of the anhydro dimer in one or more positions; and c) hydrolyzing the alkylated anhydro dimer to recover an alkylated salicylaldehyde derivative.
• anhydro dimer may be performed using any suitable conditions such as those known in the art. Typical conditions employ acid catalysis in the presence of a dehydrating agent. One such method employs an acid anhydride in the presence of sulfuric or alkyl sulfonic acid catalyst. It will be apparent to the skilled artisan that many other methods can be employed including those based on other dehydrating reagents such as thionyl chloride, phosphorous oxides, dialkyldicarbonates and the like, as well as dehydrating reaction conditions that remove water via azeotroping (Dean Stark or the like) or that rely on adsorbants to physically sequester water (such as molecular sieves, anhydrous salts or the like).
• dehydrating reagents such as thionyl chloride, phosphorous oxides, dialkyldicarbonates and the like
• dehydrating reaction conditions that remove water via azeotroping (Dean Stark or the like) or that rely on adsorbants
• hydrolysis of an anhydro dimer to recover the substituted salicylaldehyde may be performed using literature procedures. These normally employ acidic treatment in protic solvents such aqueous mineral acids, but it will be apparent to the skilled artisan that other hydrolysis conditions can be employed. Many examples are available from the literature describing the hydrolysis of acetals and ketals and any of these conditions may be employed in embodiments of the present invention.
• Chemical transformations performed at the anhydro-dimer stage can be quite varied, the only limitations being the practical ones requiring that the reagents and conditions employed do not cause a substantial degree of undesirable reaction on the bicyclic acetal moiety of the anhydro dimer and that any functional groups introduced are substantially compatible with the chemistry employed in hydrolysis of the dimers to recover the salicylaldehyde products. In some embodiments, several such reactions are performed on the anhydro dimers prior to recovery of the final substituted salicylaldehyde derivatives by hydrolysis of the dimers.
• the methods and compounds described herein are useful in the synthesis of known metal complexes and/or ligands thereof.
• methods and compounds described herein are useful in the synthesis of compounds described in WO2008136591, WO2010013948, WO2010022388, WO2009137540, WO2008150033, US2010029896, U.S. Pat. Nos. 6,870,004, 7,304,172, JP2010001443A. CN101020747, CN10229276 , J. Am. Chem. Soc., 2007, 129, p. 8082-83 , Bull. Korean Chem. Soc., 2009, Vol. 30, No. 3 p. 745-748 , Angew. Chem.
• a step of performing one or more chemical transformations on an anhydro dimer comprises performing a carbon-carbon bond forming reaction on at least one aromatic ring of the anhydro dimer in one or more positions.
• a carbon-carbon bond forming reaction on at least one aromatic ring of the anhydro dimer comprises alkylating at least one aromatic ring of the anhydro dimer in one or more positions.
• an alkylation occurs equally on both salicylaldehyde molecules comprising the anhydro dimer.
• this process entails replacing a non-carbon substituent (Q) on the aryl ring with a carbon atom.
• such a method proceeds according Scheme 1:
• R 1 represents one or more non-hydrogen substituents optionally present at one or more positions of the aryl ring(s), where each —R 1 group is independently selected and is as defined hereinbelow;
• -Q represents one or more substitutable groups present on the aryl ring(s) and “-alkyl”, represents one or more moieties that is linked to the aryl ring through a carbon atom (including aliphatic, acyl, aryl, etc.) and which is introduced on the aryl ring in place of one or more of the -Q groups.
• -Q groups in Scheme I are selected from the group consisting of —H, F, Cl, Br, I, —B(OR y ) 2 , —OSO 2 R y , and combinations of two or more of these.
• a -Q group in Scheme 1 is —H.
• an —H at the ortho, para or ortho and para positions is replaced with a carbon atom.
• an alkylation occurs at an unsubstituted aromatic ring position ortho to the hydroxyl group of the starting salicylaldehyde.
• —R x groups are as defined hereinbelow and “-alkyl” represents any moiety linked to the aryl ring through a carbon atom (including aliphatic, acyl, aryl, etc.).
• an alkylation occurs at the aromatic ring position para to the hydroxyl group of the starting salicylaldehyde. In certain embodiments, this process proceeds according to the following scheme:
• bis alkylation occurs at aromatic ring positions ortho and para to the hydroxyl group of the starting salicylaldehyde. In certain embodiments, this process proceeds according to the following scheme:
• a provided method comprises a first alkylating step using a first alkylating reagent and a second alkylating step using a second alkylating reagent wherein the first and second alkylating reagents are different.
• the first alkyating step introduces a substituent at the aryl position para to the phenol hydroxy group of the starting salicylaldehyde and the second alkylating step introduces a different substituent at the aryl position ortho to the phenol hydroxy group of the starting salicylaldehyde.
• the first alkyating step introduces a substituent at the aryl position ortho to the phenol hydroxy group of the starting salicylaldehyde and the second alkylating step introduces a different substituent at the aryl position para to the phenol hydroxy group of the starting salicylaldehyde.
• these processes proceed according to the following schemes:
• a starting salicylaldehyde is substituted at the aryl position ortho to the phenol and an alkylation step introduces a substituent at the aryl position para to the phenol hydroxyl group.
• a starting salicylaldehyde is substituted at the aryl position para to the phenol and an alkylation step introduces a substituent at the aryl position ortho to the phenol hydroxyl group.
• an alkylation transforms R 3 of an anhydro dimer from —H to an optionally substituted aliphatic group.
• an optionally substituted aliphatic group introduced at R 3 is selected from the group consisting of optionally substituted C 1-20 aliphatic, and optionally substituted aryl.
• a step of alkylating the aromatic ring comprises reacting the anhydro dimer under Friedel Crafts conditions. In certain embodiments, a step of alkylating the aromatic ring comprises reacting the anhydro dimer under Friedel Crafts alkylating or acylating conditions. Suitable reagents and conditions for Friedel Crafts reactions are well known in the art. Exemplary conditions for such transformations include, but are not limited to, those found in: ADVANCED ORGANIC CHEMISTRY. 4 th Ed. by Jerry March, pp 534-552 and the references cited therein.
• the Friedel Crafts alkylating conditions comprise reacting the anhydro dimer with at least one compound selected from the group consisting of: alkenes, alcohols, alkyl halides, and mixtures of two or more of these in the presence of a promoter selected from the group consisting of Lewis acids and proton acids.
• the step of performing a carbon-carbon bond forming reaction comprises reacting the anhydro dimer with a transition metal catalyst and a suitable reagent to introduce a new carbon-linked substituent.
• such transitional metal catalyzed carbon-carbon bond forming reactions take place between the anhydro dimer and a suitable reagent, wherein the anhydro dimer and reagent bear complementary coupling groups.
• Suitable coupling reactions are well known to one of ordinary skill in the art and typically involve either the anhydro dimer or reagent bear an electron-withdrawing group (EWG) (e.g., Cl, Br, I, OTf, OTs, OMs etc.), such that the resulting polar carbon-EWG bond is susceptible to oxidative addition by an electron-rich metal (e.g., a low-valent palladium or nickel species), and the complementary coupling group being an electropositive group (e.g., boronic acids, boronic esters, boranes, stannanes, silyl species, zinc species, aluminum species, magnesium species, zirconium species, etc.), such that the carbon which bears the electropositive coupling group is susceptible to transfer to other electropositive species (e.g., a Pd II-IV species or a Ni II-IV species).
• EWG electron-withdrawing group
• an electropositive group e.g., boronic acids, boronic esters, bora
• the step of performing a transition metal-catalyzed carbon-carbon bond forming reaction comprises reacting a position on the anhydro dimer substituted with a halogen, or similar group (i.e. a sulfonate ester or other leaving group) with a transition metal catalyst and a suitable reagent to introduce a new substituent at that position.
• the step of performing a transition metal-catalyzed carbon-carbon bond forming reaction comprises reacting a position on the anhydro dimer substituted with an atom from groups 1-2 or 12-14 (IA-IIA and IIB-IVA) of the periodic table.
• the atom is selected from the group consisting of, boron, tin, silicon, magnesium, or zinc atom with a transition metal catalyst and a suitable reagent to introduce a new carbon-linked substituent at that position.
• a transition metal catalyst and a suitable reagent to introduce a new carbon-linked substituent at that position.
• Suitable conditions, catalysts and reagents for performing such transformations are well known in the art. Suitable conditions can be found in ADVANCED ORGANIC CHEMISTRY. 4 th Ed. by Jerry March and references cited therein.
• the coupling is a Suzuki coupling.
• Suzuki coupling of boronic acids with different aryl halides is typically conducted using palladium catalysts tetrakis(triphenylphosphine) palladium (0) or another suitable source such as trans-dichlorobis(tri-o-tolylphosphine)palladium (II), Pd(II)Cl 2 (PPh 3 ) 2 , Pd(II)Cl 2 (dppb) 2 , Pd(II)(OAc) 2 +PPh 3 , Pd(II)(OAc) 2 +tri(o-tolyl)phosphine (palladacycle), or Pd/C under basic conditions.
• the reaction base is sodium or potassium or barium hydroxide, sodium or potassium bicarbonate, sodium, potassium, cesium or thallium carbonate, cesium or potassium fluoride sodium or potassium tert-butoxide, potassium phosphate or triethylamine and the solvent includes DMF, ethanol, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, water, toluene/benzene and mixtures thereof and with phase transfer reagents, such as Bu 4 NCl or 18-crown-6.
• Exemplary reactions include those described in Metal - Catalyzed Cross - Coupling Reactions , A. de Meijere and F.
• a step of performing one or more chemical transformations on an anhydro dimer comprises performing a carbon-heteroatom bond forming reaction on at least one aromatic ring of an anhydro dimer in one or more positions.
• a carbon-heteroatom bond forming reaction is selected from the group consisting of halogenation, or introduction of a group linked via an atom selected from the group consisting of: oxygen, nitrogen, sulfur, phosphorous, boron, tin, silicon, lithium, magnesium, or combinations of two or more of these.
• the anhydro dimer formed in step (a) has a formula:
• R 1 , R 2 , R 3 , and R 4 are —H, and the remainder are each independently selected from the group consisting of halogen, —NO 2 , —CN, —Si(R y ) 3 , —SR y , —S(O)R y , —S(O) 2 R y , —NR y C(O)R y , —OC(O)R y , —CO 2 R y , —NCO, —N 3 , —OR y , —OC(O)N(R y ) 2 .
• R 3 is —H in a provided salicylaldehyde derivative from which an anhydro dimer is formed.
• R 1 in a provided salicylaldehyde derivative selected from the group consisting of optionally substituted C 1-20 aliphatic, and optionally substituted aryl.
• R 1 in the provided salicylaldehyde derivative from which the anhydro dimer is formed is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, t-butyl, isoamyl, tert-amyl, and substituted phenyl.
• the present invention encompasses chemical manipulations to the anhydro dimer substituent groups themselves.
• the step of performing one or more chemical transformations on the anhydro dimer comprises performing one or more chemical reactions to manipulate functional groups already present on the anhydro dimer.
• Such reactions can include those commonly performed in organic synthesis such as reductions, oxidations, additions, protections, deprotections, cycloadditions, aminations, decarboxylations, halogenations, transition metal-catalyzed carbon-carbon bond couplings, Click reactions, ring-closing or cross metathesis reactions, and the like.
• the functional groups thus manipulated may be those attached to the aryl ring of the salicaldehyde or may be present on substituents attached to the aryl rings.
• the present invention encompasses novel compositions of matter with utility in the production of substituted salicylaldehyde compounds.
• the present invention provides the anhydro dimers disclosed in the schemes and descriptions hereinabove.
• the present invention encompasses anhydro dimers with utility in the production of salen catalysts.
• such compounds have a structure D1:
• R 1 and R 2 are independently selected from the group consisting of hydrogen, halogen, —NO 2 , —CN, —Si(R y ) 3 , —SR y , —S(O)R y , —S(O) 2 R y , —NR y C(O)R y , —OC(O)R y , —CO 2 R y , —NCO, —N 3 , —OR y , —OC(O)N(R y ) 2 , —N(R y ) 2 , —NR y C(O)R y , —NR y C(O)OR y ; or an optionally substituted radical selected from the group consisting of C 1-20 aliphatic; C 1-20 heteroaliphatic; phenyl; a 3- to 8-membered saturated or partially unsaturated monocyclic carbocycle, a 7-14 carbon saturated or partially unsaturated polycyclic
• R 1 and R 2 are independently optionally substituted radicals selected from the group consisting of C 1-20 aliphatic and C 1-20 heteroaliphatic.
• R 1 and R 2 are both t-butyl.
• the present invention provides anhydro dimers with utility in the production of salen catalysts.
• such compounds have any of structures D2 through D8:
• the invention encompasses anhydro dimers with any of structures D9 through D13:
• the invention encompasses anhydro dimers with any of structures D14 through D18:
• Q is selected from the group consisting of: bromine, chlorine, iodine, —OH, —OSO 2 R, —N(R) 2 , —N(R) 3 + , —P(R) 3 + , substituted guanidine, guanidinium, and amidine.
• Q′ is hydroxyl.
• Q′ is bromine.
• Q′ is a guanidine.
• Q′ is TBD.
• Q′ is [N-methyl TBD] + .
• Q′ is trialkylammonium.
• R 26 is selected from the group consisting of: —H, halogen, methyl, ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, and t-butyl. In certain embodiments, for compounds of formulae D14-D18, R 26 is t-butyl.
• n is an integer between 1 and 6. In certain embodiments, for compounds of formulae D14-D18, n is an integer between 2 and 5. In certain embodiments, for compounds of formulae D14-D18, n is 3 or 4.
• Zinc powder (1.28 g, 19.6 mmol) suspended in DMF (7 mL) was treated with I 2 (0.21 g, 1 mmol) under nitrogen at ambient temperature. When the red color dissipated, the mixture was warmed to 50° C., and a charge of 1-chloro-4-iodobutane (2 mL, 16.3 mmol) was added. After two hours, the anhydro dimer of 5-tert-butyl-3-bromo-2-hydroxybenzaldehyde (2.3 g, 4.6 mmol) and PdCl 2 -dppf-CH 2 Cl 2 (0.37 g, 0.45 mmol) were added. Heating at 60° C. was continued for 17 h.

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